At present, one structure of a four-wire resistive touch panel is shown in FIG. 1, a glass substrate is covered by two indium-tin oxide (ITO) transparent conductive layers (i.e., a first transparent conductive layer 1 and a second transparent conductive layer 2) serving as X electrode and Y electrode, respectively. The two ITO transparent conductive layers are covered by a PET film. The two ITO transparent conductive layers are separated from each other, the lower ITO transparent conductive layer is attached to the glass substrate, and the upper ITO transparent conductive layer is attached to the PET film. Positive and negative terminals of the X electrode and positive and negative terminals of the Y electrode are respectively led out from two ends of the X electrode and two ends of the Y electrode by conductive bars (black bar-like portions in the FIG. 1), and the conductive bar of the X electrode is perpendicular to the conductive bar of the Y electrode. The positive and negative terminals of the X electrode include a first voltage signal terminal X+ and a second voltage signal terminal X−, and the positive and negative terminals of the Y electrode includes a third voltage signal terminal Y+ and a fourth voltage signal terminal Y−, there are four connecting terminals, and that is how the four-wire resistive touch panel gets its name. When an object contacts and applies a certain pressure on a surface of the touch panel to perform touch operation on the touch panel, the upper ITO transparent conductive layer is deformed to contact the lower ITO transparent conductive layer. Such a structure may be equivalent to a corresponding circuit as shown in FIG. 2 and FIG. 3 (resistance RT at a touch point is very small and thus is ignored).
First, an X coordinate of the touch point is calculated. A driving voltage U is applied to the third voltage signal terminal Y+, the fourth voltage signal terminal Y− is grounded, and the first voltage signal terminal X+ is served as a leading terminal to measure a voltage Vx of the touch point. The ITO transparent conductive layer is homogeneously conductive. A ratio of the voltage Vx of the touch point to the driving voltage U is equal to a ratio of the X coordinate of the touch point and a width a of the touch panel, i.e., Vx/U=X/a.
Then, a Y coordinate of the touch point is calculated. A driving voltage U is applied to the first voltage signal terminal X+, the second voltage signal terminal X− is grounded, and the third voltage signal terminal Y+ is served as a leading terminal to measure a voltage Vy of the touch point. The ITO transparent conductive layer is homogeneously conductive. A ratio of the voltage Vy of the touch point to the driving voltage U is equal to a ratio of the Y coordinate of the touch point and a height b of the touch panel, i.e., Vy/U=Y/b.
The calculated coordinates of the touch point are
             ⁢      {                                        X            =                                                            V                  x                                U                            ⁢              a                                                                        Y            =                                                            V                  y                                U                            ⁢              b                                          
The inventor founds that at least following issues are existed in the related art: it can be seen from the equivalent circuit diagrams (FIG. 2 and FIG. 3) that, the first voltage signal terminal X+ is served as one leading terminal to measure the voltage Vx of the touch point when calculating the X coordinate of the touch point, and the third voltage signal terminal Y+ is served as one leading terminal to measure the voltage Vy of the touch point when calculating the Y coordinate of the touch point. In this case,
            V      x        =                            R          4                                      R            3                    +                      R            4                              ⁢      U        ,            V      y        =                            R          2                                      R            1                    +                      R            2                              ⁢              U        .            When the size of the touch panel is large, resistances of the various resistors are large, so errors of the calculated Vx of the touch point and the Vy thereof may be relatively big, thereby a calculated location (coordinates) of the touch point is not accurate, and sensitivity of the touch panel may is lower.